OBJECTIVES• Ability to diagnose and treat the signs and symptoms of NEC• Ability to evaluate radiographs for the classic findings of NEC• List several long-term complications associated with NEC
NECROTIZING ENTEROCOLITIS• Epidemiology: – most commonly occurring gastrointestinal emergency in preterm infants – leading cause of emergency surgery in neonates – overall incidence: 1-5% in most NICU’s – most common in VLBW preterm infants • 10% of all cases occur in term infants
NECROTIZING ENTEROCOLITIS• Epidemiology: – 10x more likely to occur in infants who have been fed – males = females – blacks > whites – mortality rate: 25-30% – 50% of survivors experience long-term sequelae
NECROTIZING ENTEROCOLITIS• Pathology: – most commonly involved areas: terminal ileum and proximal colon – GROSS: • bowel appears irregularly dilated with hemorrhagic or ischemic areas of frank necrosis – focal or diffuse – MICROSCOPIC: • mucosal edema, hemorrhage and ulceration
NECROTIZING ENTEROCOLITIS• MICROSCOPIC: – minimal inflammation during the acute phase • increases during revascularization – granulation tissue and fibrosis develop • stricture formation – microthrombi in mesenteric arterioles and venules
RISK FACTORS• Infectious Agents: – usually occurs in clustered epidemics – normal intestinal flora • E. coli • Klebsiella spp. • Pseudomonas spp. • Clostridium difficile • Staph. Epi • Viruses
RISK FACTORS• Inflammatory Mediators: – involved in the development of intestinal injury and systemic side effects • neutropenia, thrombocytopenia, acidosis, hypotension – primary factors • Tumor necrosis factor (TNF) • Platelet activating factor (PAF) • LTC4 • Interleukin 1& 6
RISK FACTORS• Circulatory Instability: – Hypoxic-ischemic injury • poor blood flow to the mesenteric vessels • local rebound hyperemia with re-perfusion • production of O2 radicals – Polycythemia • increased viscosity causing decreased blood flow • exchange transfusion
RISK FACTORS• Enteral Feedings: – > 90% of infants with NEC have been fed – provides a source for H2 production – hyperosmolar formula/medications – aggressive feedings • too much volume • rate of increase – >20cc/kg/day
RISK FACTORS• Enteral Feedings: – immature mucosal function • malabsorption – breast milk may have a protective effect • IGA • macrophages, lymphocytes • complement components • lysozyme, lactoferrin • acetylhydrolase
From UpToDate online, Adapted from Kliegman, RM, Pediatr Res 1993; 34:701.
CLINICAL PRESENTATION Gestational age: Age at diagnosis: < 30 wks 20 days 31-33 wks 11 days > 34 wks 5.5 days Full term 3 days*Time of onset is inversely related to gestational age/birthweight
CLINICAL PRESENTATIONGastrointestinal: SystemicFeeding intolerance LethargyAbdominal distention Apnea/respiratory distressAbdominal tenderness Temperature instabilityEmesis HypotensionOccult/gross blood in stool AcidosisAbdominal mass Glucose instabilityErythema of abdominal wall DIC Positive blood cultures
• ADDENDUM• Review of the images reveal air lucency noted in both hypochondrial regions which• are worrisome for free gas. There is also suggestion of portal venous gas.• ***FINAL ADDENDUM*** Verified by: Dr PCC, Registrar,• Amended Date/Time: 30-MAR-2005 09:27• ORIGINAL REPORT• HISTORY• High NG aspirates• REPORT• The small bowel loops are dilated and there is faecal material noted in the large• colon but not much in the rectum. However, no definite pneumotosis intestinalis• is seen. Tip of the NG tube is in the distal oesophagus rather than the stomach• and should be adjusted.• CONCLUSION• The small bowel is dilated. The cause however is not visualised in the study.
• ORIGINAL REPORT• HISTORY• ? sepsis. Growing prem. Abdominal distension.• REPORT• CXR - MOBILE SUPINE AP• Compared with CXR from 14/12/2004.• NG tube is again noted. There is now bilateral perihilar peribronchial thickening.• Cardiac size is unremarkable.• The intestinal loops remained gaseously distended though faecal matter is seen within• the colon. There is a lack of rectal air through a catheter is seen in the lower• pelvic cavity.
• ORIGINAL REPORT• HISTORY• Septicaemia. NEC. Intubated.• REPORT• MOBILE SUPINE (CHEST AND ABDOMEN)• The tip of the NG tube is projected over the distal esophagus. The tip of the ETT• is about 0.6cm from the carina.• A tube is projected over the rectal area.• There is diffuse haziness of both lungs. The heart size cannot be assessed.• There are multiple gas distended intestinal loops and intraperitoneal free gas present• which appears worse when compared to the last AXR.
• ORIGINAL REPORT• HISTORY• NEC, septic shock on CPAP, IA and IV lines.• REPORT• AXR - SUPINE AP• Compared with AXR taken 10 hours earlier.• The nasogastric tube is now seen projected over the left hypochondrium. There is• interval worsening of the gaseously distended intestinal loops. Faecal matter is• again seen in the proximal colon. No air or faecal matter seen in the pelvic cavity.• There is free extraluminal air within the peritoneal cavity, outlining the liver.• Riglers sign is noted, consistent with intestinal perforation.
Rigler signRiglers sign, also known as the double wall sign, is seen onan x-ray of the abdomen when air is present on both sides of the intestine, i.e. when there is air on both the luminal and peritoneal side of the bowel wall.
BELL STAGING CRITERIASTAGE CLINICAL X-RAY TREATMENTI. Suspect Mild abdominal Mild ileus Medical distention Work up for NEC Poor feeding Sepsis EmesisII. Definite The above, plus Significant Medical Marked abdominal Ileus NEC distention Pneumatosis GI bleeding Intestinalis PVGIII. Advanced The above, plus Pneumo- Surgical Unstable vital signs Peritoneum NEC Septic Shock
RADIOLOGICAL FINDINGS• Pneumatosis Intestinalis – hydrogen gas within the bowel wall • product of bacterial metabolism a. linear streaking pattern • more diagnostic b. bubbly pattern • appears like retained meconium • less specific
RADIOLOGICAL FINDINGS• Portal Venous Gas – extension of pneumatosis intestinalis into the portal venous circulation • linear branching lucencies overlying the liver and extending to the periphery • associated with severe disease and high mortality
RADIOLOGICAL FINDINGS• Pneumoperitoneum – free air in the peritoneal cavity secondary to perforation • falciform ligament may be outlined – “football” sign• Ultrasound – Good for bedside demonstration of ascites – May show portal air more clearly than KUB – surgical emergency
Surgical treatment• Stage IIIa - IIIb – Laparotomy • Resection of necrotic bowel • Ileostomy with mucous fistula – Subsequent re-anastamosis • May result in strictures requiring further surgery later – Peritoneal drain • Placement in NICU under local anesthetic • Used when infant is too clinically unstable for surgery • May help stabilize pt for subsequent surgery
HistopathologyNormal NEC:small Hemorrhagicbowel necrosis beginning at the mucosa and working its way down into the wall http://library.med.utah.edu/WebPath/PEDHTML/PED045.html
Histopathology Pneumatosis in the submucosa of the small bowelhttp://library.med.utah.edu/WebPath/PEDHTML/PED049.html
PROGNOSIS• Depends on the severity of the illness• Associated with late complications * strictures – short-gut syndrome – malabsorption – fistulas – abscess * MOST COMMON
Outcomes• Mortality varies with birth weight: – <1000 g = 40-100% – <1500 g = 10-44% – >2500 g = 0-20%• Morbidity/Mortality vary with severity: – Resection -> Short gut -> FTT, malabsorbtion – Strictures -> further surgery in medical and surgical NEC – Prolonged NPO status on TPN -> cholestasis & metabolic abnormalities
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